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I've had no luck searching Google for terms like RCA power connector, other than a passing reference on Wikipedia. I have plenty of RCA connectors, and tons of wall warts. I've got a small LED desk lamp that I want to power with a wall wart instead of a battery, but I don't have any female connectors that the wall warts plug into.

So my thought was to use an adapter and change the end to be an RCA connector. If I'm putting a few volts and maybe 500mA or so, would there be any problem as far as the RCA connectors go? Obviously I'll need to reduce the voltage for the LED and I'll have to deal with those concerns, but if there's any problems with the connector I'll just try to find some standard connectors.

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  • \$\begingroup\$ What a great question! I have been trying to finagle ps/2 ports for my bike 12v battery project because I have a drill press and need round connectors. But RCA is way easier! Plus I have a million rca cables sitting around! \$\endgroup\$ – Jeshii May 7 '15 at 22:46
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In my experience RCA plugs make a very tight connection, and I expect the resistance to be way less than 50 mΩ, probably near 10 mΩ. Even at 2 times 50 mΩ (you have to count both pin and sleeve) a 500 mA current will cause a 25 mW dissipation, which is more than acceptable.

Matt makes a valid point about mixing them up with audio plugs, though. The wall-wart probably has a DC jack like this

enter image description here

Why not use a socket for that? These are almost exclusively used for power supplies, so there's little chance of confusing them for something else. Sockets for them are readily available.

enter image description here

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  • \$\begingroup\$ +1, those sockets come in a variety of shapes and sizes, for through-hole PCB mount and case mount alike. \$\endgroup\$ – Polynomial Jul 24 '12 at 6:03
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There are even commercial products around that do exactly what you suggest. Note the black RCA connector on this cheapo satellite receiver labeled "12V OUT =50mA".

RCA connector used for DC power

It is probably used to power a relay that switches all your other home entertainment devices on or off when the receiver is on or in standby.

I assume they decided to use an RCA connector because it was cheapest for them, and it is quite obvious that you must be extra careful to not fry your audio or video equipment by accidental, wrong connections.

As I said: Cheapo!

The amount of current you can run over your RCA connection depends heavily on the exact type of connector. Here's an example of one that is specified at an amazing value of 16 A. There are others I wouldn't use for more than 100 mA.

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The obvious risk is that someone could plug the wall adapter into an RCA jack somewhere else, potentially frying your stereo or theirs.

The next concern would be whether the connector can handle 500mA without getting warm due to resistance in the metal part or in a poor connection between the plug & jack due to surface dirt etc. 500mA isn't a tremendous amount of current, but keep in mind that RCA jacks were designed to carry signal, not power. You might try it on the lab bench and give up on it if you find the connector getting noticeably warm. If you have a meter that can measure resistance down to milliohms try measuring the entire assembly from the far ends of the wire to get an idea how much power it will dissipate (\$P=I^2R\$).

It sounds like you plan to change the plug end on the wall adapter cable as well as adding a matching jack to the lamp. You might as well buy a matching pair of parts from Digikey or similar so you know they're rated for that much current or more.

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  • \$\begingroup\$ From what I understood of his question the reason he's considering using RCA is because he has a matching pair handy (not ordering any parts or waiting for them to ship). \$\endgroup\$ – Shamtam Jul 24 '12 at 4:24
  • \$\begingroup\$ @Shamtam, precisely. I could order some parts from somewhere, but if I've got the parts on hand... \$\endgroup\$ – Wayne Werner Jul 24 '12 at 12:10
  • \$\begingroup\$ +1 for mentioning the possibility of plugging it into circuits not meant to handle that sort of power. I think if I do go ahead and use the RCA connectors I'll have to put the female end on the wall wart - I have children and if they're anywhere near as inquisitive as I was, I foresee them putting power where it wasn't intended (or, like I did, plugged my Erector set motor into an AC outlet. After all if it spun real fast with a D cell battery, it should spin REALLY fast with AC, right? pop goes the motor :-\ \$\endgroup\$ – Wayne Werner Jul 24 '12 at 12:19
  • \$\begingroup\$ @Wayne Ha ha! When I was a kid, my dad had an old lamp cord in his workshop and one day I thought it would be cool to plug it in and short the ends together to see what would happen. It made an awesome spark and then all the lights in the basement went out. I thought I "broke the house" for a moment and then remembered there was such a thing as the fuse box. After the lights were back on I went to see what had happened to the wire and the ends had melted, scattering little balls of molten copper all over the floor. Was very glad none went in my eyes! \$\endgroup\$ – Matt B. Jul 24 '12 at 18:34
  • \$\begingroup\$ @Wayne With kids in the house, I'd consider wrapping the connection in electrical tape once you're confident it works. Maybe even hardwiring it with no jack if you don't plan to switch back & forth between battery and wall power. Also try to pick a wall adapter with a fuse in it. \$\endgroup\$ – Matt B. Jul 24 '12 at 18:35
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There shouldn't be any issues transferring power through an RCA connector, especially for low power applications. The only reason I would suggest against it is that RCA connectors tend to be quite wide with their tolerance ranges and could come apart easier than you'd want (meaning your circuit loses power as soon as it comes disconnected), however, if you're not moving the connection around or putting any mechanical stress on it, you shouldn't have problems. After you get it setup, I'd just double-check the connection's security and make sure neither contact is heating up, which could indicate a shoddy connection.

I've used RCA connectors to power two 12V Sanyo Denki 120mm DC Fans for my computer a long time ago. Had no issues.

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I've often used them at about 5A. They get a bit warm towards the higher end but I haven't had one melt (so far). I standardised on using red ones for 5V and yellow for 12V, same as ATX wiring.

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Easy to short the output of an RCA male cable.. not necessarily a problem if the power source doesn't mind being short-circuited.

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The RCA connector can handle 48v and 3amp. I have this arrangement on a electric bike battery charging circuit. What is important is that the cables used can also handle that current without getting hot enough to melt the insulation. Voltage rating below 48v not a problem

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When I was younger, I made a battery bank from a yard of sink drain pipe filled with 9 D-cell batteries, for research purposes (making stuff spark and glow).

For connecting this battery bank to the outside world, I used two RCA connectors; one wired as positive (outer shell and inner pin in parallel) and another wired as negative.

I'm unsure of the current my (rechargable) batteries were capable of pushing, but 5-10A seems a reasonable ball park estimate. The RCA connectors could get warm when performing a lot of... research, but they never gave me any problems.

At 500mA, I think you'll be fine.

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apple used RCA connectors for power connectors on the white iBooks until they switched over to magsafe connectors, so it is definitely feasible.

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  • 3
    \$\begingroup\$ Those were a custom coaxial connector, not RCA. \$\endgroup\$ – duskwuff Jul 19 '14 at 16:41

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